Lead telluride structure

Similar to PbSe, the controlled growth of lead telluride, PbTe, on (111) InP was demonstrated from aqueous, acidic solutions of Pb(II) and Cd(II) nitrate salts and tellurite, at room temperature [13]. The poor epitaxy observed, due to the presence of polycrystalline material, was attributed to the existence of a large lattice mismatch between PbTe and InP (9%) compared to the PbSe/InP system (4.4%). The characterization techniques revealed the absence of planar defects in the PbTe structure, like stacking faults or microtwins, in contrast to II-VI chalcogenides like CdSe. This was related to electronic and structural anomalies. 

The next substance to be discussed is the first one without structure. It is lead telluride, PbTe, where lead is iso-morphously substituted by tin in the range 15 to 19%. The substance will be encoded as one component with several fragments ... 

The structural chemistry of the actinides is often similar to that of lighter transition metals, such as Zr and Hf, and to that of the lanthanides however, the diffuse nature of the 5/ orbitals leads to some differences and specifically to interesting magnetic and electrical properties. The actinide sulfides are generally isostructural with the selenides, but not with the analogous tellurides. The binary chalcogenides of uranium and thorium have been discussed in detail [66], but the structural... 

The tin(II) and lead(II) tellurides result from the amide M N(SiMe3)2k and tellurol. The tin derivative is dimeric with the Sn2Te2 unit adopting a butterfly-like structure with the terminal tellurol groups cis109. The antimony and bismuth derivatives result from amides and the tellurol96. 

A major portion of the effort on semiconductors has been expended on the binary compounds having the zinc blende or wurtzite structure. These are commonly classified by the A group numbers such as III-V (InAs) and II-VI (CdTe) and have what may loosely be described as a 1 to 1 cation-anion ratio. However, another series of compounds that has become of increased interest can be generally classified as the IV-VI compounds. Specifically, these are the chal-cogenides of germanium, tin, and lead. In this discussion, we present some experimental observations on the tellurides of these group IV A elements. 

The valence-region x-ray photoelectron spectra of the lead chalcoge-nides have been reported by McFeely et al. (1973) as Fig. 6.7(a) shows, there is a remarkable similarity between the sulfide, selenide, and telluride. Band-structure calculations (e.g., Tung and Cohen, 1969 Rabii and... 

None of these methods is utterly satisfactory. The use of alkali-metal solutions in liq NH3 allows intercalation from Li to Cs to be covered. It can readily be used to prepare nonstoichiometric phases but the method presents experimental difficulties. Ammonia is often cointercalated, which favors the formation of trigonal prismatic intercalates owing to the preference of the NH3 for this type of site. On the other hand, the solvation of the A ions by NH3 may determine the composition of the final product in relation to the formation of stable complex species, with a definite formulation, between the slabs of the host. The thermal treatment necessary to remove the NHj may also lead to different structures than those formed at RT it certainly plays a role concerning the phase limits. Alkali-metal solutions in liq NH3 are powerful reducing solutions, and in the case of tellurides, or even for some selenides or sulfides, a reduction of the host structure can occur. 

The ability to control product formation, the reproducibility of results, and the relatively mild conditions under which the reactions proceed, have made cluster syntheses by this method very attractive. Furthermore, the starting materials are themselves readily prepared and easily stored and handled. This is especially valuable in metal telluride chemistry, in which suitable reagents for cluster syntheses are often unstable and must be generated in situ, leading to complex mixtures of reaction products. The use of the silylated tellurium reagents Te(TMS)2 and RTe-TMS has allowed access to a wealth of metal tellurium clusters with unique structures and properties. " ... 

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